The present invention relates to oscillators, and more particularly, to oscillators with sampling current compensation for offsetting drift variations.
Oscillator circuits are found in many electronic circuit applications and are often used for generating clock signals that control the timing of circuits or control the logic state of a device. For example, oscillator circuits can be used in conjunction with many circuits such as DC/DC converters, audio receivers, counters, shifters, microprocessors and FM (frequency modulation) circuitry. Typically, the frequency of the clock signal provided by an oscillator circuit is determined primarily by charging and discharging of one or more capacitors. Such charging and discharging is often controlled by constant current sources or current mirrors supplying charge currents to the capacitors and the discharging is effected by controlling transistors coupled across the capacitors. However, ambient temperature variations and process drift can cause variations in electrical characteristics of these capacitors and transistors thereby causing the frequency of the clock signal to vary. It would therefore be beneficial if oscillator circuits could be configured to reduce the effects of clock signal frequency variations caused by ambient temperature variations.